/Engine/Source/Runtime/Engine/Classes/Animation/AttributesContainer.h
Tries to find and return the indedx of a attribute type/value entry of the specified AttributeType.Indexto the entry, INDEX_NONE if not found
int32 IndexOfByKey ( const [UScriptStruct](API\Runtime\CoreUObject\UObject\UScriptStruct) * InScriptStruct, const [FAttributeId](API\Runtime\Engine\Animation\FAttributeId) & InAttributeId ) const